JPWO2009031550A1 - Ranging device - Google Patents

Abstract

Provided is a distance measuring device capable of measuring a distance from a far-distance object to a short-distance object by using a light receiving element of the same size. A transmission optical system 20 that projects signal light toward a target object and a reception optical system 30 that receives the signal light reflected from the target object and has a different optical axis are connected to the transmission optical system. In the distance measuring apparatus 100 that includes a light receiving element 12 disposed on an image plane and measures a distance to a target object from a time difference between transmission and reception of the signal light, the reception optical system 30 includes: A distance measuring apparatus 100 having a variable focal length optical system 14 that makes a focal length of a receiving optical system variable.

Description

  The present invention relates to a distance measuring device using laser light.

2. Description of the Related Art Conventionally, a distance measuring device is known that irradiates a target object with a laser beam, receives the reflected light, and obtains the distance to the target object from the time difference between transmission and reception (for example, Japanese Patent Laid-Open No. 63-244001). No. publication). In recent years, it has been desired that the distance measuring device can measure the distance of a near object.
However, in the conventional distance measuring device, the optical axis of the transmission optical system and the optical axis of the reception optical system are different. Therefore, when trying to measure the distance of a near object using a light receiving element of the same size, the target object The spot image of the reflected light of the laser beam from the laser beam forms an image outside the light receiving element area arranged in the vicinity of the imaging surface of the receiving optical system, and there is a limit to the measurable distance of short-distance objects was there.

The present invention has been made in view of such problems, and an object thereof is to provide a distance measuring device that can measure a distance from a far-distance object to a short-distance object using a light-receiving element of the same size. To do.
In order to solve the above-described problem, the first aspect of the present invention provides a transmission optical system that projects signal light toward a target object, and the signal reflected by the target object, the optical axis of which differs from the transmission optical system. A receiving optical system for receiving light; and a light receiving element disposed on an imaging plane of the receiving optical system, and measuring a distance to the target object from a time difference between transmission and reception of the received light. In the distance measuring device, the imaging position of the signal light reflected by the target object at a long distance by the receiving optical system and the imaging of the signal light reflected by the target object at a short distance by the receiving optical system There is provided a distance measuring device characterized in that an imaging position adjusting means capable of adjusting a position with respect to the light receiving element is provided in the receiving optical system.
According to the first aspect of the present invention, it is desirable that the imaging position adjusting unit is a variable focal length optical system that makes a focal length of the receiving optical system variable.
According to the first aspect of the present invention, it is preferable that the variable focal length optical system includes a variable magnification optical system disposed between the objective lens of the receiving optical system and the light receiving element.
According to the first aspect of the present invention, it is desirable that the variable focal length optical system includes a removable optical system between the objective lens of the receiving optical system and the light receiving element.
According to the first aspect of the present invention, it is desirable that the variable focal length optical system has a removable optical system on the object side of the objective lens of the receiving optical system.
According to the first aspect of the present invention, the longest focal length of the receiving optical system is fL, the shortest focal length of the receiving optical system is fS, and the object to be measured is changed by the variable focal length optical system. When the maximum distance of L1 is L1 and the minimum distance is L2, it is desirable to satisfy the following conditional expression.
(L2 / L1) × fL ≦ fS ≦ fL
According to the first aspect of the present invention, it is desirable that the imaging position adjusting unit is an optical axis deflection optical system that deflects the optical axis of the reception optical system.
According to the first aspect of the present invention, it is desirable that the optical axis deflection optical system includes a mirror.
According to the first aspect of the present invention, it is desirable that the optical axis deflection optical system includes a declination prism.
According to the first aspect of the present invention, the imaging position adjusting means is reflected by the target object at a short distance from the imaging position of the signal light reflected by the target object at the long distance. It is desirable that the light receiving element holding mechanism be arranged so that the center of the light receiving element is shifted along the image forming position direction of the signal light.
According to the first aspect of the present invention, it is preferable that the distance measuring device further includes a collimating optical system.
According to the present invention, it is possible to provide a distance measuring device that can measure a distance from a far-distance object to a short-distance object using a light-receiving element of the same size.

FIG. 1 is a schematic configuration diagram of an optical system of the distance measuring apparatus according to the first embodiment.
FIG. 2 is a diagram for explaining the positional relationship of laser spot images from target objects having different distances on the light receiving element of the light receiving optical system.
FIG. 3 is a schematic diagram showing a light receiving element and each spot image position.
FIG. 4 is a schematic configuration diagram of an optical system of the distance measuring apparatus according to the second embodiment.
FIG. 5 is a schematic configuration diagram of an optical system of a distance measuring device according to the third embodiment.
FIG. 6 is a schematic configuration diagram of an optical system of a distance measuring apparatus according to the fourth embodiment.
FIG. 7 is a diagram for explaining the positional relationship of laser spot images from target objects having different distances on the light receiving element of the light receiving optical system.
FIG. 8 is a schematic diagram showing the light receiving elements arranged in the vicinity of the intersection line and the positions of the respective spot images.
9A and 9B are diagrams for explaining the effect of mirror tilt.
FIG. 10 is a schematic configuration diagram of an optical system of a distance measuring apparatus according to the fifth embodiment.
11A and 11B are diagrams of only the light receiving optical system for explaining the operation of the declination prism.
FIG. 12 is a schematic configuration diagram of an optical system of the distance measuring apparatus according to the sixth embodiment.
FIG. 13 is a diagram illustrating the positional relationship of laser light images from target objects having different distances on the light receiving element of the light receiving optical system.
FIG. 14 is a schematic diagram showing a light receiving element and each light spot position.

A distance measuring apparatus according to a first embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic configuration diagram of an optical system of the distance measuring apparatus according to the first embodiment. FIG. 2 is a diagram for explaining the operation of the distance measuring apparatus according to the first embodiment. FIG. 3 is a schematic diagram showing a light receiving element and each light spot position.
In FIG. 1, the distance measuring device 100 according to the first embodiment includes a transmission optical system 20 in which the optical axis A1 of the transmission optical system and the optical axis A2 of the collimation optical system have a common optical axis A, and the optical axis A. And a receiving optical system 30 having an optical axis B different from the above. For simplification, electronic circuit portions such as a signal light driving circuit, a control circuit, an arithmetic circuit, and a display device are omitted.
Light emitted from the light source 2 such as a semiconductor laser (hereinafter referred to as signal light) is emitted along the optical axis A1 of the transmission optical system 20, and is provided in the erecting prism 4 to transmit the signal light and reflect the visible light. After passing through the dichroic mirror 3, it is reflected by the mirror surface 4a, travels toward the objective lens 1, and is irradiated from the objective lens 1 onto a target object (P1, P2, PF, PN, etc. in FIG. 2). The erecting prism 4 is an erecting roof prism, but may be an erecting poro prism.
The signal light reflected by the target object and the visible light from the target object are collected by the objective lens 1 and enter the upright prism 4. The signal light is reflected by the mirror surface 4 a of the erecting prism 4, passes through the dichroic mirror 3, and is emitted to the light source 2 side. In this way, the transmission optical system is configured.
Visible light is reflected by each reflecting surface including the dichroic mirror 3 of the erecting prism 4 and exits the erecting prism 4 to form an image of the target object on the reticle 5. The objective lens 1 is shared by the transmission optical system and the collimation optical system.
The reticle 5 is engraved with an index such as a crosshair, and the transmission optical system and the collimation optical system have a common optical axis A. Therefore, the eyepiece 6 uses the target object image and the cross on the reticle 5. By overlapping the line, the signal light can be accurately irradiated to the target object. In this way, a collimating optical system is configured.
The receiving optical system 30 is arranged with a predetermined distance (d to be described later) from the common optical axis A of the transmitting optical system and the collimating optical system, and the signal light and the visible light from the target object are received optically. A spot image is formed on a light receiving element 12 disposed in the vicinity of the imaging surface of the objective lens 11 through the objective lens 11 of the system. Further, only the light of the wavelength of the signal light passes through the objective lens 11 side of the light receiving element 12 in order to eliminate the influence of background light (noise light) such as sunlight illuminating the target object incident on the light receiving element 12. In addition, a narrow band filter 13 that cuts light of other wavelengths is provided.
Since the narrow band filter 13 transmits light having the same wavelength as the signal light, it is desirable that the size of the light receiving element 12 is set to a minimum and sufficient size to improve the S / N ratio of the signal light. .
Further, a variable focal length optical system 14 that varies the focal length of the reception optical system 30 is disposed between the objective lens 11 and the light receiving element 12 of the reception optical system 30. The variable focal length optical system 14 includes a negative lens group 14A and a positive lens group 14B from the objective lens 11 side, and the focal length of the reception optical system 30 is variable by moving the negative lens group 14A along the optical axis B. To. The negative lens group 14A may be moved in at least two stages and the focal length may be varied in at least two stages. Alternatively, the negative lens group 14A and the positive lens group 14B may be moved continuously. Alternatively, the focal length may be made variable.
In this way, the distance measuring device 100 is configured.
In the distance measuring apparatus 100 according to the first embodiment, the center position of the light receiving element 12 is the image plane of the reception optical system 30 as shown in FIGS. The center of the light receiving element is shifted from the position along the imaging position direction of the signal light of the short-distance object. That is, the center of the light receiving element 12 is positioned so that the one end 12a of the light receiving element 12 is positioned in the vicinity of the optical axis B and the other end 12b is away from the optical axis B on the imaging plane of the receiving optical system 30. They are staggered. And by having the variable focal length optical system 14, the range which can be measured as described later can be expanded.
The light receiving element 12 is arranged perpendicular to the optical axis B of the receiving optical system 30, but is not necessarily perpendicular, and the position of the light receiving element 12 is, for example, the best image of a spot image corresponding to the closest distance. It is preferable to dispose it at a point position.
Hereinafter, the position of the light receiving element 12 of the distance measuring device 100 according to the first embodiment and the distance measurement possible range will be described with reference to FIGS. 2 and 3. The same components as those in FIG.
In FIG. 2, the signal light emitted from the light source 2 is reflected by a mirror surface 4 a that is disposed on the erecting prism 4 and transmits visible light and reflects signal light, and then passes through the objective lens 1 and reaches the target object P <b> 1. Reach (longest measurement distance). The upright prism 4 shown in FIG. 1 is omitted from the description.
The signal light is scattered by the object P 1, and a part of the signal light enters the objective lens 11 of the reception optical system 30. The signal light travels along a straight line C connecting the center of P1 and the center of the objective lens 11, and forms an image at a point Q1 near the optical axis B on the light receiving element 12 arranged in the vicinity of the imaging surface of the objective lens 11. The distance to the target object P1 is calculated from the time difference between transmission and reception.
Assuming that the distance to the object P1 is L1, a deviation δ1 of the point Q1 from the optical axis B is expressed by the equation (1).
(1) δ1 = f × d / L1
Here, f represents the focal length of the objective lens 11, and d represents the gap between the optical axis A and the optical axis B.
When the distance L1 is sufficiently larger than the gap d, d / L1 is substantially zero and δ1 is also substantially zero. This means that the point Q1 is on the optical axis B. Therefore, in consideration of measuring up to a long distance L1 with respect to d, it is preferable to arrange the one end portion 12a of the light receiving element 12 on the optical axis B. However, when a limit is set on the distance L1 in consideration of the reach distance of the signal light or the received light intensity of the signal light, the one end 12a at the position of the light receiving element 12 is slightly separated from the optical axis B according to (1). You may arrange.
On the other hand, when measuring the object P2 at the short distance L2, the position where the signal light from P2 enters the objective lens 11 along the optical path D and forms an image is defined as Q2 (the distance from the optical axis B is δ2). ), It is expressed by equation (2) in the same manner as equation (1).
(2) δ2 = f × d / L2
Here, when the size of the light receiving element 12 is M, the short distance that can be measured is represented by Equation (3) when δ2 = M and L2 is expressed.
(3) L2 = f × d / M
According to the above equation (3), it can be seen that the distance L2 can be shortened by increasing the size M of the light receiving element 12 or by shortening the focal length f of the receiving optical system 30.
However, if the size of the light receiving element 12 is increased, the distance L2 can be shortened. However, for the reasons described above, S / N deterioration is increased by light other than signal light, and the maximum distance L1 is shortened, which is not preferable. .
In the distance measuring device 100 according to the first embodiment, the variable focal length optical system 14 is disposed between the objective lens 11 and the light receiving element 12 of the receiving optical system 30 and the focal length f is shortened, thereby making the distance closer. It is possible to measure the distance.
1 and 2, the position of the light source image in the light receiving element 12 when the negative lens group 14A is moved to the objective lens 11 side and the focal length is changed from the maximum focal length fL to the minimum focal length fS of the receiving optical system 30. When the object position corresponding to Q1 is PF, the distance is LF, the object position corresponding to Q2 is PN, and the distance is LN, the following relational expression is established.
(4) LF = (fS / fL) × L1
(5) LN = (fS / fL) × L2
From equations (4) and (5), it can be seen that when the focal length f of the receiving optical system 30 is changed from fL to fS, the measurement distances LF and LN change in proportion to the focal length ratio.
Further, it is desirable that the minimum focal length fS satisfies the following conditional expression.
(6) (L2 / L1) × fL ≦ fS ≦ fL
The upper limit value of the equation (6) is clear from the gist of the invention, but the lower limit value is a distance region (L2 and LF) where the distance LF becomes shorter than the distance L2 and the distance cannot be measured when the focal length of the receiving optical system 30 is shortened. This is for the purpose of preventing (between).
The conditional expression (6) is a condition for changing the focal length of the receiving optical system 30 discontinuously, for example, at least two steps from fL to fS, and the variable focal length optical system 14 continuously increases the focal length. This is a condition that does not need to be taken into account when the zoom zooming optical system is changed dynamically.
Hereinafter, the case where the focal length is changed in two steps will be described as a representative of the expression (6). From FIG.
(7) d / L1 = δ1 / fL
(8) d / LF = δ1 / fS
From these two formulas,
(9) LF = (fS / fL) × L1
It becomes.
Conditions that prevent the creation of distance areas that cannot be measured are as follows:
(10) L2 ≦ LF
Therefore, from the equations (9) and (10),
(11) (L2 / L1) × fL ≦ fS
Is obtained. Since the upper limit value of fS is the maximum focal length fL, fS needs to satisfy the expression (6).

Assuming that fL = 100 mm, d = 30 mm, and L1 = 500 m, δ1 = 0.006 mm from equation (1). Further, if the size M (length) of the light receiving element 12 is 0.05 mm, L2 = 53.6 m from the equation (3).
As shown in FIG. 1, assuming that the focal length fS = 50 mm when the negative lens group 14A is moved in the direction of the objective lens 11, from equation (4), LF = 250 m, from equation (5), LN = 26. .8m.
As a result, the distance measuring device 100 according to the first embodiment can reduce the distance that can be measured from L2 = 53.6 m to LN = 26.8 m. Therefore, the distance measuring device 100 can perform distance measurement in a range from L1 = 500 m to LN = 26.8 m.

Assuming that fL = 100 mm, d = 30 mm, and L1 = ∞, δ1 = 0.0 mm from the equation (1). Further, if the size M (length) of the light receiving element 12 is 0.05 mm, L2 = 60 m from the equation (3).
As shown in FIG. 1, assuming that the focal length fS = 50 mm when the negative lens group 14A is moved in the direction of the objective lens 11, from equation (4), LF = ∞, and from equation (5), LN = 30 m It becomes.
As a result, the distance measuring device 100 according to the first embodiment can shorten the distance at which the short distance can be measured from L2 = 60 m to LN = 30 m.
In FIG. 3, reference numeral A <b> 11 indicates a point where the optical axis A is projected onto a surface including the imaging surface of the objective lens 11. SA schematically shows the spot size of the signal light, and the light receiving element 12 is arranged so as to include at least SA so that it does not become larger than SA. / N can be improved, and it is possible to measure at a longer distance as well as at a shorter distance. In addition to the rectangular shape, the light receiving element 12 can achieve the same effect by using a circular shape, an elliptical shape, or a rectangular shape other than the rectangular shape.
(Second Embodiment)
FIG. 4 is a schematic configuration diagram of an optical system of the distance measuring device 200 according to the second embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.
In the second embodiment, the variable focal length optical system 15 is detachable between the objective lens 11 and the light receiving element 12 of the receiving optical system 30.
The variable focal length optical system 15 includes, in order from the objective lens 11 side, a positive lens group 15A and a negative lens group 15B. By inserting the variable focal length optical system 15 into the optical axis B, the focal length of the reception optical system. Can be changed from fL to fS.
The operation of the variable focal length optical system 15 is the same as that of the first embodiment, and detailed description thereof is omitted. Needless to say, as in the first embodiment, the minimum focal length fS needs to satisfy the conditional expression (6). Other operations and effects are the same as those in the first embodiment, and a description thereof will be omitted.
(Third embodiment)
FIG. 5 is a schematic configuration diagram of an optical system of the distance measuring device 300 according to the third embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.
In the third embodiment, the variable focal length optical system 16 is configured to be detachable on the object side of the objective lens 11 of the reception optical system 30.
The variable focal length optical system 16 includes, in order from the object side, a negative lens group 16A and a positive lens group 16B. The variable focal length optical system 16 is an afocal optical system that can be attached to and detached from the objective lens 11, and is attached to the object side of the objective lens 11. The focal length of the receiving optical system can be changed from fL to fS. Mounting is performed by screws or fitting.
The operation of the variable focal length optical system 16 is the same as that of the first embodiment, and detailed description thereof is omitted. Needless to say, as in the first embodiment, the minimum focal length fS needs to satisfy the conditional expression (6). Other operations and effects are the same as those in the first embodiment, and a description thereof will be omitted.
In the first to third embodiments, even when the optical axis A1 of the transmission optical system is different from the optical axis A2 of the collimation optical system, the optical axis A1 of the transmission optical system and the optical axis B of the reception optical system. The same effect can be obtained if the relationship between and satisfies the relationship described above.
In the first to third embodiments, the case where the center of the light receiving element 12 is shifted from the optical axis B has been described. However, even when the center of the light receiving element 12 coincides with the optical axis B, It goes without saying that by arranging the variable focal length optical system according to the embodiment, the ranging distance can be made variable and the ranging range can be expanded.
As described above, in addition to the distance between the transmission optical system and the reception optical system, the distance measurement apparatus includes a coaxial distance measurement apparatus in which these are overlapped. In the case of coaxial, the position of the target image on the light receiving element does not change depending on the distance to be measured, so there is no limitation on the distance measuring range depending on the size of the light receiving element, but instead, the transmitted light and received light are separated by a half mirror, etc. However, there is a disadvantage that the intensity of received light decreases and the maximum distance measurement distance decreases, but such a problem does not occur in the distance measurement apparatus according to the present embodiment.
As described above, according to the distance measuring apparatus according to the first to third embodiments, even if the size of the light receiving element is the same, the focal length is long by changing the focal length of the receiving optical system. In this case, it is possible to perform distance measurement of a long-distance object, and when the focal distance is short, it is possible to perform distance measurement up to a close distance, and it is possible to achieve a distance measuring device capable of selecting a distance measurement mode according to the application.
(Fourth embodiment)
FIG. 6 is a schematic configuration diagram of an optical system of the distance measuring apparatus according to the fourth embodiment. FIG. 7 is a diagram for explaining the operation of the distance measuring apparatus according to the fourth embodiment. FIG. 8 is a schematic diagram showing a light receiving element and each light spot position. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.
In the fourth embodiment, a mirror 17 that deflects the optical axis B of the receiving optical system 30 is disposed at a predetermined angle with respect to the optical axis B between the objective lens 11 and the light receiving element 12 of the receiving optical system 30. Has been. The position of the optical image on the light receiving element 12 is changed by changing the mirror 17 from the tilt angle by a predetermined angle (angle α in FIG. 9B).
In this way, the distance measuring device 100 is configured.
In the distance measuring device 400 according to the fourth embodiment, the center position of the light receiving element 12 is the imaging surface of the receiving optical system 30 as described later, and the distance of the object at a short distance from the imaging position of the signal light of the object at a long distance. The center of the light receiving element is shifted along the image forming position direction of the signal light. That is, as shown in FIGS. 7 and 8, one end 12 a of the light receiving element 12 is positioned in the vicinity of the optical axis B and the other end 12 b is moved away from the optical axis B on the imaging plane of the receiving optical system 30. The center of the light receiving element 12 is shifted so as to be positioned. The mirror 17 makes it possible to enlarge the range that can be measured as will be described later.
The light receiving element 12 is arranged perpendicular to the optical axis B of the receiving optical system 30, but is not necessarily perpendicular, and the position of the light receiving element 12 is, for example, the best spot image corresponding to the closest distance. It is preferable to dispose it at the image point position.
Hereinafter, the position of the light receiving element 12 of the distance measuring apparatus 100 according to the fourth embodiment and the distance measurement possible range will be described with reference to FIGS. 7 and 8. The same components as those in FIG.
In FIG. 7, the signal light emitted from the light source 2 is transmitted through the visible light and reflected by the dichroic mirror 4 a that reflects the signal light disposed on the erecting prism 4, and then passes through the objective lens 1 and the target object P <b> 1. P2 is reached from (the longest measurement distance). The upright prism 4 shown in FIG. 6 is omitted from the description.
The signal light is scattered by the object P 1, and a part of the signal light enters the objective lens 11 of the reception optical system 30. The signal light travels along a straight line C connecting the center of P1 and the center of the objective lens 11, and forms an image at a point Q1 in the vicinity of the optical axis B on the light receiving element 12 disposed in the vicinity of the imaging surface of the objective lens 11. The distance to the target object P1 is calculated from the time difference between transmission and reception.
Assuming that the distance to the object P1 is L1, a deviation δ1 of the point Q1 from the optical axis B is expressed by the equation (1).
(1) δ1 = f × d / L1
Here, f represents the focal length of the objective lens 11, and d represents the gap between the optical axis A and the optical axis B.
When the distance L1 is sufficiently larger than the gap d, d / L1 is substantially zero and δ1 is also substantially zero. This means that the point Q1 is on the optical axis B. Therefore, in consideration of the measurement up to a long distance L1 with respect to d, it is preferable to arrange the one end portion 12a of the light receiving element 12 on the optical axis B. However, when the distance L1 is limited in consideration of the reach distance of the signal light or the received light intensity of the signal light, the position of the light receiving element 12 may be slightly separated from the optical axis B according to (1). Good.
On the other hand, when the position at which the signal light from the object P2 at the position of the short distance L2 enters the objective lens 11 along the optical path D and forms an image is Q2 (the distance from the optical axis B is δ2), (1) Similar to the equation, it is expressed by equation (2).
(2) δ2 = f × d / L2
Here, when the size of the light receiving element 12 is M, the short distance that can be measured is represented by the following equation (3) when L2 is expressed as δ2 = M.
(3) L2 = f × d / M
According to the above equation (3), the size M of the light receiving element 12 may be increased in order to shorten the distance L2.
However, if the size of the light receiving element 12 is increased, the distance L2 can be shortened. However, for the reasons described above, the S / N deterioration is increased by light other than the signal light, and the maximum distance L1 is shortened. .
Further, when attempting to measure the distance to the object P3 that is closer than the distance L2, the spot image of the signal light from the object P3 is positioned on the imaging plane of the light receiving element 12 at the Q3 position (the distance from the optical axis B). (δ3), and δ3 is expressed by equation (12).
(12) δ3 = f × d / L3
Since the position Q3 of δ3 is not on the light receiving element 12, the distance cannot be measured as it is.
In the distance measuring device 400 according to the fourth embodiment, the mirror 17 is disposed between the objective lens 11 of the receiving optical system 30 and the light receiving element 12, and the optical axis B is deflected by the mirror 17, so that the light is received on the light receiving element 12. A spot image is formed, and it is possible to measure the distance to a closer distance.
9A and 9B are diagrams for explaining the operation when the tilt angle of the mirror 17 is changed. FIG. 9A shows a state in which the distance is measured between the distance L1 and the distance L2, and FIG. 9B shows a state in which the distance L3 is measured from the distance L2.
In FIG. 9A, the mirror 17 is supported in a state tilted at a predetermined angle with respect to the optical axis B. In this state, the signal light from the distance L1 enters along the optical axis C, is reflected by the mirror 17, and forms an image on Q1 of the light receiving element 12. The signal light from the distance L2 enters along the optical axis D, is reflected by the mirror 17, and forms an image on Q2 of the light receiving element 12. Thereby, the distance measuring device 400 can measure the distance of the object between the distance L1 and the distance L2.
Next, when measuring the distance of an object closer than the distance L2, the distance measuring device 400 tilts the mirror 17 with respect to the optical axis B by a predetermined angle α by operating a member (not shown). As a result, the signal light from the distance L2 is reflected by the mirror 17 and forms an image at the Q1 position of the light receiving element 12, and the signal light from the distance L3 is reflected by the mirror 17 and forms an image at the Q2 position of the light receiving element 12. . In this way, by tilting the mirror 17 by the predetermined angle α, the imaging position Q2 at the distance L2 before tilting is set to the imaging position Q1 after tilting, and the imaging position Q3 at the distance L3 before tilting is imaged after tilting. It can be deflected to position Q2. As a result, the distance measurement possible range of the distance measuring device 400 can be changed from the distance L2 to the distance L3.
At this time, the relationship between the distance L3 and the distance L2 is expressed by the following equation (13).
(13) L3 = δ2 / (2δ2-δ1) × L2
Specific examples are shown below.

In the case of a distance measuring device with f = 100 mm, d = 30 mm, L1 = 500 m, and L2 = 100 m,
From equation (1), δ1 = 0.006 mm, from equation (2), δ2 = 0.03 mm, and by inclining the mirror 17 from equation (13), L3 = 55.6 m. Therefore, by tilting the mirror 17, distance measurement from L2 = 100 m to L3 = 55.6 m becomes possible.
As a result, the distance measuring apparatus according to the third embodiment includes the tilting mirror 17, thereby enabling distance measurement in the range of L1 = 500 m to L3 = 55.6 m.

In the case of a distance measuring device with f = 50 mm, d = 30 mm, L1 = ∞, L2 = 50 m,
Δ1 = 0 mm from equation (1), δ2 = 0.03 mm from equation (2), and tilting the mirror 17 from equation (13) enables distance measurement from L2 = 50 m to L3 = 25 m.
As a result, the distance measuring apparatus according to the fourth embodiment has the mirror 17 that is inclined, thereby enabling distance measurement in a range from L1 = ∞ to L3 = 25 m.
As described above, the distance measurement range from L1 to L2 before tilting the mirror 17 becomes the distance measurement range from L2 to L3 after the mirror 17 is tilted.
Therefore, when it is desired to measure the distance to the object P3, the distance can be measured by tilting the mirror 17.
The tilt angle α of the mirror 17 is an amount by which the corresponding position Q2 of the target object P2 on the light receiving element 12 is moved to the position Q1, but when the mirror 17 is tilted beyond this, the target object P3 is moved to the position Q1. Although the distance to the near object can be measured further beyond the distance, the spot image of the target object P <b> 2 exceeds the size of the light receiving element 12 on the light receiving element 12, so that a range that cannot be measured is generated. In order to avoid this, it is desirable that the inclination angle α of the mirror 17 is in a range where the spot image of the target object P2 does not exceed the size of the light receiving element 12. That is, the tilt angle α of the mirror 17 is desirably set so that the object P2 is included from the objects P1 to P2 before the tilt and from the object P2 to P3 after the tilt.
In the fourth embodiment, the deflection direction of the optical axis B by the mirror 17 is set to a direction away from the optical axis A in the plane defined by the optical axis A and the optical axis B. However, the deflection direction is Not limited to this, it may be deflected in a direction intersecting with the optical axis A. By deflecting in the direction crossing the optical axis A, the distance measuring device 400 can be made smaller. Alternatively, it can be deflected in an arbitrary direction centered on the optical axis B in a plane orthogonal to the optical axis B, and can be set as appropriate when designing the distance measuring apparatus 400.
Further, it is desirable that the mirror 17 has a lock mechanism that fixes the tilt angle at the start point and the end point so as not to rotate carelessly.
(Fifth embodiment)
FIG. 10 is a schematic configuration diagram of an optical system of a distance measuring apparatus 500 according to the fifth embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.
In the fifth embodiment, the declination prism 18 is disposed between the objective lens 11 and the light receiving element 12 of the reception optical system 30, and the declination prism 18 is moved along the optical axis. The optical axis B is configured to be deflectable in a plane including the optical axis A and the optical axis B.
11A and 11B are views of only the receiving optical system for explaining the operation of the deflection prism 18. FIG. 11A shows the initial position, the distance measurement from L1 to L2 in FIG. 7, and FIG. 11B the deflection prism. , And a case where the distance is measured from L2 to L3 in FIG.
11A and 11B, before the declination prism 18 is moved, the imaging position of the signal light from P1 incident on the receiving optical system 30 is Q1, and the imaging position of the signal light from P2 is Q2. In the range 500, the distance measurement range is set from L1 to L2.
Next, the declination prism 18 is moved Z along the optical axis B in the direction of the light receiving element 12 in order to enable distance measurement in the range from L2 to L3. As a result, the imaging position of the signal light from P2 moves to Q1, the imaging position of the signal light from P3 moves to Q2, and can be detected by the light receiving element 12. As a result, the distance measuring device 500 can measure the range from L2 to L3.
11A and 11B, the inclination β of the optical axis by the deflection prism 18 is expressed by the following equation (14), where n is the refractive index of the deflection prism 18 and α is the apex angle.
(14) β = (n−1) × α
The movement amount ε of the optical axis when the declination prism 18 is moved by Z along the optical axis B in the direction of the light receiving element 12 is expressed by the following equation (15).
(15) ε = βZ = (n−1) × α × Z
Therefore, by moving the declination prism 18, a margin of ε is generated on the light receiving element 12, and distance measurement at a short distance becomes possible.
The equivalent effect can be achieved by moving the light receiving element 12 or arranging a plurality of light receiving elements. However, it is difficult to move the light receiving element along with the substrate in terms of accuracy. Increases size.
Further, when a plurality of light receiving elements are arranged, it is not necessary to move the substrate, but the light receiving elements cannot be brought close to each other without a gap, and therefore, an unmeasurable distance region corresponding to the gap occurs.
It is also desirable to have a lock mechanism that fixes the moving position of the declination prism 18.
In the fourth and fifth embodiments described above, the case where the center of the light receiving element 12 is shifted from the optical axis B has been described, but even when the center of the light receiving element 12 coincides with the optical axis B, It goes without saying that the distance-measuring distance can be varied by arranging the optical axis deflecting member according to the fifth embodiment.
As described above, in addition to the distance between the transmission optical system and the reception optical system, the distance measurement apparatus includes a coaxial distance measurement apparatus in which these are overlapped. In the case of coaxial, the position of the target image on the light receiving element does not change depending on the distance to be measured, so there is no limitation on the distance measuring range depending on the size of the light receiving element, but instead, the transmitted light and received light are separated by a half mirror, etc. However, there is a disadvantage that the intensity of received light decreases and the maximum distance measurement distance decreases, but such a problem does not occur in the distance measuring apparatus according to the fifth embodiment.
As described above, according to the distance measuring apparatus according to the fourth and fifth embodiments, even if the size of the light receiving element is the same, the optical means for deflecting the optical axis of the receiving optical system is used, Ranging (rotating) or moving the signal light imaging position on the light receiving element is variable, especially by extending the distance measuring range on the near distance side, ranging from the distance measurement of a long distance object to the closest distance Thus, it is possible to achieve a distance measuring device capable of selecting a distance measuring mode according to the application.
(Sixth embodiment)
A distance measuring apparatus 600 according to a sixth embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.
FIG. 12 is a schematic configuration diagram of an optical system of the distance measuring apparatus according to the sixth embodiment. FIG. 13 is a diagram for explaining the positional relationship of the spot images of signal light from target objects having different distances on the light receiving element of the receiving optical system. FIG. 14 is a schematic diagram showing a light receiving element and each spot image position.
In the distance measuring device according to the sixth embodiment, the center position of the light receiving element 12 is a short distance from the imaging position of the signal light reflected by the long-distance object on the imaging surface of the receiving optical system 30 as will be described later. The center of the light receiving element is shifted and arranged along the image forming position direction of the signal light reflected by the object. That is, as shown in FIGS. 13 and 14, one end portion 12 a of the light receiving element 12 is positioned in the vicinity of the optical axis B and the other end portion 12 b is moved away from the optical axis B on the imaging surface of the light receiving optical system 30. The center of the light receiving element 12 is shifted so as to be positioned. In this way, by disposing the light receiving elements 12 in a shifted manner, it is possible to expand the range that can be measured as will be described later.
The light receiving element 12 is arranged perpendicular to the optical axis B of the receiving optical system 30, but is not necessarily perpendicular, and the position of the light receiving element 12 can be arranged at the best image point position of the spot image. preferable.
Hereinafter, the position of the light receiving element 12 of the distance measuring apparatus 600 according to the sixth embodiment and the distance measurement possible range will be described with reference to FIGS. 13 and 14.
In FIG. 13, the signal light emitted from the light source 2 is reflected by a mirror surface 4 a that transmits visible light and reflects signal light disposed on the erecting prism 4, and then passes through the objective lens 1 to reach the target object P <b> 1 ( P3 (short-range target object) is reached from the longest measurement distance. Note that the erecting prism 4 shown in FIG.
The signal light applied to the far target object P 1 is reflected (scattered) by the object P 1, and a part of the signal light enters the objective lens 11 of the reception optical system 30. The signal light travels along a straight line C connecting the center of P1 and the center of the objective lens 11, and forms an image at a point Q1 in the vicinity of the optical axis B on the light receiving element 12 disposed in the vicinity of the imaging surface of the objective lens 11. The distance to the target object P1 is calculated from the time difference between transmission and reception.
Assuming that the distance to the object P1 is L1, a deviation δ1 of the point Q1 from the optical axis B is expressed by the equation (1).
(1) δ1 = f × d / L1
Here, f represents the focal length of the objective lens 11, and d represents the gap between the optical axis A and the optical axis B.
When the distance L1 is sufficiently larger than the gap d, d / L1 is substantially zero and δ1 is also substantially zero. This means that the point Q1 is on the optical axis B. Therefore, in consideration of the measurement up to a long distance L1 with respect to d, it is preferable to arrange the one end portion 12a of the light receiving element 12 on the optical axis B. However, when the distance L1 is limited in consideration of the reach distance of the signal light or the received light intensity of the signal light, the position of the light receiving element 12 may be slightly separated from the optical axis B according to (1). Good.
On the other hand, when the position at which the signal light from the object P2 at the intermediate distance L2 enters the objective lens 11 along the optical path D and forms an image is Q2 (the distance from the optical axis B is δ2), (1) Similar to the equation, it is expressed by equation (2).
(2) δ2 = f × d / L2
Similarly, assuming that the position where the signal light from the object P3 at the closest distance L3 enters the objective lens 11 along the optical path D and forms an image is Q3 (the distance from the optical axis B is δ3), (12 ).
(12) δ3 = f × d / L3
Here, when the light receiving element 12 is arranged so that the center thereof overlaps the optical axis B as in the prior art (see X in FIG. 13), since the size of the light receiving element 12 can only cover the imaging points Q1 to Q2, distance measurement is performed. The possible distance is limited to L1 to L2, and the closest distance L3 cannot be measured. Further, since there is a region (reference numeral XA in FIG. 13) on the optical axis A side with respect to the optical axis B of the light receiving element 12, S / N deterioration due to light other than the signal light is unavoidable, and the maximum distance L1 is also shortened. .
If the size of the light receiving element 12 is increased with the conventional arrangement of the light receiving element 12, it is possible to measure the distance of the object P3 at a close distance, but the region on the optical axis A side becomes larger than the optical axis B described above, S / N degradation is increased by light other than signal light, and the maximum distance L1 is further shortened.
In the distance measuring device 600 according to the sixth embodiment, as shown in FIGS. 13 and 14, the one end portion 12 a of the light receiving element 12 of the same size is arranged in the vicinity of the optical axis B, and the other end portion 12 b is set to the optical axis B. By shifting the center of the light receiving element 12 away from the center, the signal light from the short-distance object P3 can be imaged on the light receiving element 12. As a result, only by shifting the center position of the light receiving element 12, distance measurement from a long distance to a short distance is possible as compared with a conventional distance measuring device.
Here, when the size of the light receiving element 12 is 2M, the measurable short distance in the conventional arrangement is (f × d / M), whereas in the distance measuring device 600 of the sixth embodiment, The short distance that can be measured is (f × d / 2M), and the distance can be measured to almost half the short distance.
For example, when f = 100 mm of the objective lens 11, the gap d = 30 mm between the optical axis A and the optical axis B, and the length 2 M = 0.5 mm of the light receiving element 12, the short distance that can be measured by the conventional arrangement is 12 m. On the other hand, in the case of the distance measuring device 600, the short distance that can be measured can be reduced to 6m and 1/2.
In FIG. 14, reference symbol A <b> 11 indicates a point where the optical axis A is projected onto a surface including the imaging surface of the objective lens 11. S and SA schematically indicate the spot size of the signal light. The light receiving element 12 is disposed so as to include at least SA, and the signal light is not excessively larger than SA. S / N can be improved, and it is possible to measure at a longer distance as well as at a shorter distance. In addition to the rectangular shape, the light receiving element 12 can achieve the same effect by using a circular shape, an elliptical shape, or a rectangular shape other than the rectangular shape.
Even when the optical axis A1 of the transmission optical system is different from the optical axis A2 of the collimation optical system, the relationship between the optical axis A1 of the transmission optical system and the optical axis B of the reception optical system satisfies the relationship described above. If it is, the same effect can be produced.
As described above, in addition to the distance between the transmission optical system and the reception optical system, the distance measurement apparatus includes a coaxial distance measurement apparatus in which these are overlapped. In the case of coaxial, the position of the target image on the light receiving element does not change depending on the distance to be measured, so there is no limitation on the distance measuring range depending on the size of the light receiving element, but instead, the transmitted light and received light are separated by a half mirror, etc. However, there is a drawback in that the intensity of received light decreases and the maximum distance measurement distance decreases, but such a problem does not occur in the distance measuring apparatus according to the sixth embodiment.
As described above, according to the distance measuring apparatus according to the sixth embodiment, the center of the light receiving element 12 is shifted to a position away from the optical axis B of the receiving optical system, thereby receiving light of the same size as that of the conventional art. While using the element 12, it is possible to achieve a distance measuring device that can measure a distance to a near object and can measure a distance equivalent to that of a conventional object.
The above-described embodiment is merely an example, and is not limited to the above-described configuration or shape, and can be appropriately modified and changed within the scope of the present invention.

Claims (14)

A transmission optical system that projects signal light toward a target object;
A receiving optical system for receiving the signal light reflected by the target object, and having an optical axis different from that of the transmitting optical system;
A light receiving element disposed on the imaging surface of the receiving optical system,
In a distance measuring device that measures the distance to the target object from the time difference between transmission and reception of the received light,
The light receiving element represents the imaging position of the signal light reflected by the target object at a long distance by the receiving optical system and the imaging position of the signal light reflected by the target object at a short distance by the receiving optical system. A distance measuring apparatus comprising an imaging position adjusting means that can be adjusted with respect to the receiving optical system.   The distance measuring apparatus according to claim 1, wherein the imaging position adjusting unit is a variable focal length optical system that makes a focal length of the receiving optical system variable.   The distance measuring apparatus according to claim 2, wherein the variable focal length optical system includes a variable magnification optical system disposed between an objective lens of the receiving optical system and the light receiving element.   The distance measuring apparatus according to claim 2, wherein the variable focal length optical system includes an optical system that can be inserted and removed between an objective lens of the receiving optical system and the light receiving element.   The distance measuring apparatus according to claim 2, wherein the variable focal length optical system includes a removable optical system on the object side of the objective lens of the receiving optical system. The longest focal length of the receiving optical system changed by the variable focal length optical system is fL, the shortest focal length of the receiving optical system is fS, the maximum distance to the object to be measured is L1, and the minimum distance is L2. The range finder according to claim 2, wherein the following conditional expression is satisfied.
(L2 / L1) × fL ≦ fS ≦ fL The longest focal length of the receiving optical system changed by the variable focal length optical system is fL, the shortest focal length of the receiving optical system is fS, the maximum distance to the object to be measured is L1, and the minimum distance is L2. The range finder according to claim 3, wherein the following conditional expression is satisfied.
(L2 / L1) × fL ≦ fS ≦ fL The longest focal length of the receiving optical system changed by the variable focal length optical system is fL, the shortest focal length of the receiving optical system is fS, the maximum distance to the object to be measured is L1, and the minimum distance is L2. The range finder according to claim 4, wherein the following conditional expression is satisfied.
(L2 / L1) × fL ≦ fS ≦ fL The longest focal length of the receiving optical system changed by the variable focal length optical system is fL, the shortest focal length of the receiving optical system is fS, the maximum distance to the object to be measured is L1, and the minimum distance is L2. The range finder according to claim 5, wherein the following conditional expression is satisfied.
(L2 / L1) × fL ≦ fS ≦ fL   2. The distance measuring apparatus according to claim 1, wherein the imaging position adjusting means is an optical axis deflecting optical system for deflecting an optical axis of the receiving optical system.   The distance measuring apparatus according to claim 10, wherein the optical axis deflection optical system includes a mirror.   The distance measuring apparatus according to claim 10, wherein the optical axis deflection optical system includes a declination prism.   The imaging position adjusting means is arranged along the imaging position direction of the signal light reflected by the target object at the short distance from the imaging position of the signal light reflected by the target object at the long distance, The distance measuring device according to claim 1, wherein the distance measuring device is a light receiving element holding mechanism that is arranged by shifting a center of the light receiving element.   The distance measuring apparatus according to claim 1, further comprising a collimating optical system.

Images